Conveyer driving means for sheet cutting and stacking devices



March 2, 1954 TRECKER 2,670,955

G. s CONVEYER DRIVING MEANS FOR SHEET CUTTING AND STACKING DEVICES FiledAug. 24, 1950 10 v O u 4 \\OO/G,O 9

Fag-3 Patented Mar. 2, 1 954 CONVEYER DRIVING MEANS FOR SHEET CUTTINGAND STACKING DEVICES Gerald Strecker, Darmstadt-Eberstadt, Germany,

assignor of one-half to Kommandit-Gesellschaft, or limited liabilitycompany, Dr. Otto C. Strecker, Darmstadt-Eberstadt, Germany, acorporation of. Germany; and one half to Maschinenfabrik-zum BruderhansGesellschaft mit beschriinkter Haftung, Reutlingen, Germany, acorporation of Germany Application August 24, 1950, Serial No. 181,128

which the web is fed at high speed and the cut ter makes many cuts perminute.

Its purpose is to ensure the satisfactory operation of such machines,even at very high 2 Claims. (Cl. 27176') speeds, and to facilitate theinitial setting of the machines and minimize the waste of material atthe beginning of their operation.

As is well known such machines comprise supply means for feeding the webto be severed from 1 a supply roll, a transverse cutter which seversinto sheets the web so fed to it, a high speed conveyor or take-offmeans to take the cut sheets from the cutter, a low-speed conveyor whichreceives'the sheets in overlapped condition from the high-speedconveyor, and a sheet deliveryimeans or ejector which takes the sheetsfrom the low-speed conveyor and stacks them in a pile. In addition themachine comprises means for driving all these parts at suitable andrelated speeds. There may be additional or auxiliary elements, such asmountings for spare feed rolls; lengthwise cutters for slitting the web'lengthwise, means for grooving or-scoring the web, and so forth; thesedo not affect the sub stance of the invention and are hereinafterdisregarded.

A principal object of this invention is a machine of this kind forcutting webs transversely having means for driving the sheet deliverymechanism or ejector wholly independently of the drive of the supplymeans, transverse cutter and high-speed conveyor or take-off mechanism,together with means for driving the lowspeed conveyor at a speed whichis dependent on both the speed of the supply means, transverse cutter orhigh speed conveyor and the speed of the sheet delivery means.

A further object of the invention is a driving means for the low-speedconveyor which drives that conveyor at a speed which for high speeds ofthe supply means, transverse cutter and highspeed conveyor is determinedmainly by the speed of those parts and for low speeds of thoseparts isdetermined mainly by the speed of the independently driven sheetdelivery means.

Yet another object of the invention is a ma'- chine for transverselycutting paper and like webs in which the sheet delivery means is drivenindependently of the web supply means, transverse cutter and high-speedconveyor and the 2 low-speed conveyor is driven through a differentialgear one member of which is driven with the supply means, transversecutter and highspeed conveyor, and another member of which .is drivenwith the sheet delivery means, so that the speed of the low-speedconveyor is dependent on the speeds of the supply means and of thedelivery means and preferably is approximately one-eighth of their sum.

Further objects of the invention will appear from the followingdescription.

"The invention is illustrated by the accompanying drawings in which- 7Figure 1 is a diagrammatic showing of the essential parts of a machinefor severing webs transversely, as seen'in a lengthwise section of themachine;

Figure 2 is a block diagram illustrating an existing method of drivingthe parts of such a machine; and Y 7 Figure 3 is a block diagramillustrating the driving of the parts of such a machine in accordancewith the invention.

. In the machine shown in Figure 1 one or more webs of paper, or, othermaterial'run from supply rolls I through collecting rolls 2 whichexpress air from between the webs, past a lengthwise cutter 3 ifsuch isrequired to draw-in rolls 4'Whi0h draw'the. web from the supply rollsand feed it to the transverse cutter, which comprises aknife blade 5upon a'rotating drum co-operating with a fixed blade 6. By these cuttersthe web is divided into sheets of the desired width and length. From thetransverse cutter the,

sheets are taken by a high-speed conveyor com-v prisingendless belts androllers I, 8 and these :feed the sheets in overlapped relation to alowspeed conveyor comprising broad stiff endless bands 9 andco-operatingrollers Hi. This conveyor5 greatly reduces the speed of the sheets and'feeds them to a sheet delivery mechanism or ejector 12, [3 which stacksthem in a pile or piles 1M- In such machines there are four speeds tobe,

' distinguished. There is first the speed at-the draw-in rolls 4,'which'is the speed the web of paper or other material to be severed has fromthe moment i of leaving the supply rolls I until it reaches thetransverse cutter 5, 6; hereinafter this is called the supply'speed.There is next the ward by the blade of the transverse cutter. Thirdlythere is the speed of the overlap belts, that is to say of the conveyorbelts 9' upon" which the paper is braked, and upon which the sheets areoverlapped or slid one upon the other by the high-speed conveyor 1, 8;this is hereinafter called the overlap speed; naturally it much lessthan the take-oil speed; its-valuemustbe particularly carefully chosenandsuited to the various conditions of operation; There; is fourthly thespeed in the ejector orsheet delivery rolls l2, l3 of the pilingmechanism; hereirf called; the ejection speed; this must be keptwithindefinite. and quite narrow limits under all hnditions' of operation; ifthe ejection sheet is too lhiig the sheets come to a standstill beforethey reach" their end position; if it is too high they bounce back fromthe abutment against which the sheets are piled; in neither case is atidy pile obtained: 7

Another factor to be reckoned with in addition to fl-i''se s eeds thenumber of cutsper unit of ti'fiie" herein called the transverse cuttingspeed;

Thereare other speeds of drive to be pro vidd for the machine; forinstance the drive ofsash-my rope; of the lengthwise cutters, of scenesmeans and so forth? but they need not considered here they are notaffected the i fivllt io'n} bl'ng most-1y derived directly from thesupply speed. H v i v transverse sitters hitherto known drives at thefour speeds mentioned are usually obtained fr6- 5.- variable speed driveby the use of a transmission gear, commonly a variable ratio gear; foreach spree. some drives may be derive-ll ffdr'r'i others; for examplethemain drive may actuate the overlap belts or low=speed oon veyor, andthe latter may drive the eiecto'r-l In= thse' hiail'li'fis; ones th'"several transmission gears Have been" decided upon, all the speeds ofdrive are dependent on or proportional to the specs of the new drivetothe draw-"in rolls, that isto the supply speed. v

The adjustment ofth' several vaiiable drives, to' determine the le'r'igtlf ofshe-awe and soifofth is first fiectetl at a} low s eed of thedrive; only when the several gears have been selected and test sheetsbegin to come out satisfactorily is the speed of rotation; aridther'efdre the su'p ply speed, increased to"- a;- working value: whenthis is done alt the other speeds increase;- so if theeieetion speed wasinitially adjusted tba sat mam-my value; ever-i to the satisfac to'ryvalue} it may easily increase" beyond the to erable iii-nit. Upon theoverlap" speed depends the length of free travelof the cut sheets, thatis the" free length of the sheet issuing. fromthe take=ofi conveyor atthe instant whenits front edge slides over the rear edge of thepreceding sheet; if this free length is too great the sheets catchone inthe other and are not overlappedin' orderly fashion.- The risk of thisis specially great at high speeds at which air resistance plays a part,forcing down the edge of the issuing sheet notwithstanding the usuallengthwise bending, of the sheet to stiffen it; As the supply-speed increases the overlap speedshould by no means increase proportionally;

For these reasonstherefore adjustment of sev; eral transmission gearsiscalled for as the speed of the main drive is increased;

Since now the machine operator has to regulate the speed of supplyaccording to the condition ofthe rolls and other factors, thetake-offspeedaccord-ing to the requirements of the out and the overlapspeed according to the requirements or the pile stacking, his task isdifllcult. The consequence is that it is a common practice to adjustthe'take-off arid overlapspeed's toreasonable relative values While themachine is running slowly, and, because of the difiiculty of adjustingtosuit three factors, to make no attempt to reagejustto fresh-workingconditions at high speeds. Moreover; since the operator cannot overseefrom his position the requirements at all three elemerits some machinethere is special risk of things going: wrong at high speeds, so that itis c'ommoii to'operateat moderate speeds.

0n this accounb it has already been proposed "ravine aspeciar auxiliarymotor for the sheet prons:- which drives these rolls and thedv'rlaipb'elts through an overrunnin or one-way clutch at a minimumallowable speed while the main motor is running slowly, and to allow themoin'mom'r on speeding up to take over the drive through a secondone-way clutch. This certainly obviates diiiiculties during: slowrunning or the machine; but at medium an'cl high" speeds; be cause thedrives are dependent onthe" speed ofthe drive, the difiioulties aboveindicated remain and prevent full use" being made of the machine:-

It has also already beenaproposed to separate the drive oftheslow-running parts beyond the take ofi mechanisms that is of the overlapcon: voyorandejector, from. the maindrive of the machine-,- and to drivethese parts: independently of the main drive from a separate variablespeed motor; This makesit" possible to adjust the ejection speed to asuitable val-ire but? givesrise. to d-i-flicul-tie'sin respect ofoverlapping. Since the: eject-ion sp'eed may not fallbelowabout 20'metres per minute, there is no overlapping; at all at starting As thesupply speed and take=of speed increase overlapping must; beginand it isvery diiiioult toreitect' the change to overlap condition's at mediumspeeds.t During acceleration there rmrst at no timebe too large a freelength of ShOliy and so acceleration must be effected insteps and theoperator must looitout for the'instantatthe-:last issued sheet isdep0slted= on the overlap conveyor But with large and heavy supply rollsupon, a). wide maechine acceleration is: very di-fiicultand as arulecannot be eitected quiekly-eriouglrh The diflieultymay belessened byreducing the-overlap speed (and ejection speed); but even so sometimeelapses before'the first" overlapped sheets; reach the pile; in-i themeantime the not overlapped sheets arriving are too; slow, stick; andcause difiic-ulties at the pile, so that: overlap is often,

disregard-ed; These diifioulties, are still g t-eater if sheets of twosizes are being cut at the same time:

It is to overcome these difliculties that" the inc-rvention makes useota separate variable speed drive for thesheet delivery mechanism alone,a. drive which is ataallspeeds; independent oi the main drive; andderives;v the overlap speedboth from, thesupply speed (or from a speeddepend-- enton; it) and-also from the ejectionspeed; in suchfashion thatat low speeds of drive (low supply speed) the overlap speed dependsmainly on the ejectionspeed while at high; speeds of drive, itdependsmainly on the supply s-peedpr a speed derived therefrom.Morespecificallythe invention proposes the driving of the conveyor bandsby a differential gear having members driven respectively at theejection speed or a or a speed derived therefrom.- A- suitable conestruction of gear is'one ofsuch ratios that the driven member of thegear drives the overlap conveyor at'a speed equal to, or approximatelyequal to, one eighth of the sum of the ejection speed and supply speed.

As a result of this scheme the machine opera tor has only to adjust thespeeds of the supply and take-01f mechanism which he can oversee at aglance, .while the man 'at the stack can 'adjust the ejection speed togive perfect piling. Moreover, because of the influence of the ejec-.tion speed upon the overlap speed the ratio of the latter to thesupply-speed (or the take-01f speed) is greater at low working speedsthan at high working speeds, and the free length of 'the issuing sheetsdiminishes as the working speed and the effect of air resistanceincrease. So a free length ,of sheet adjusted at a lowworking speed willthe more certainly be within safe limits at a higher working speed. Sothe. invention not only simplifies and facilitates the control of themachine but also -makes possible the attainment of higher speeds thanhitherto.

The high-speed conveyor bands I, 8 run at a take-off speed b which issomewhat greater than the supply speed '0. The ratio of these speeds ishere called the factor of load. On the lowspeed conveyor 9 the roll Ibears with adjustable pressure at a distance from the end frame I I ofthe take-off mechanism equal to the length of sheet L. Because of thelesser speed of the conveyor 9 the sheets slide one over the other uponthe conveyor like the tiles of a roof. The number of sheets overlapped,or the degree of overlap is u being the overlap speed, that is, thespeed of the conveyor 9. To ensure that the leading edge of the sheetissuing from the high speed conveyor I, 8 remains out of contact withthe low-speed conveyor S'until it has passed the rear edge of thepreceding sheet upon the conveyor 9, the sheets are bent lengthwise inwell known manner to stiffen them. None the less the length :1 of freeexit of the sheet must not be too great. This length, which is alsoknown as the factor of risk. is

if the distance between two sheets is Beyond the overlap conveyor thesheets come to the sheet delivery mechanism consisting of the rolls l2and I3 with the belts etc. thereto belonging, and by these they are slidupon the pile l4 at an ejection speed s. The ejection speed must be keptwithin definite limits, dependent on the size and kind of paper, saybetween 20 and 80 metres per minute, and must be maintained for a whileafter the supply of paper has been stopped in order that the severedsheets upon the conveyors beyond the cutter may be automaticallystacked. The ejection speed may be greater or less "than the overlapspeed. Iii the former case the overlap is momentarily re-" duced, in thelatter case increased. I

Figure 2 shows the scheme of drive of the ele'-' ments of a transversecutter machine most usual. hitherto. Driving means comprising a motor Mvand-a continuously variable gear (P0, or alter-. natively a variablefspeed motor,'drive the draw'-.l in rolls 4 at the supply speed 12, andalso drive various auxiliary devices which need not be considered here.This same driving means also drives, through continuously variable gearsGQ,- Gb and Gu respectively, the cutter drum carrying} blade 5 at aspeed of revolution Q, thetake-off rolls 1, 8 at speed b and the overlapbelts! at speed a. The drive of the ejector rolls 42' and i3 is derived,usually through anon-variable gear Gs, from the overlap conveyor. Insome schemes used hitherto the speed 21. is derived not directly fromspeed 22 but from speed I). As already-men tioned' it has also beenproposed to' drive the members having speeds s and u from a specialauxiliary motor through an over-running clutch, this motor ensuring aminimum speed of these elements, above which the drive is taken overthrough another one-way clutch by the main driving means Mr Gv asalready described. The.

above.

To obviate these disadvantages the invention employs the scheme of driveshown in Figure 3. Here there is no connection at all between the maindriving means Me, Go and the sheet delivery mechanism IZ, l3. The latteris driven by separate driving means consisting of a motor Ms andvariable gear Gs (or a variable speed motor) at a speed which isindependently adjustable whatever the supply'speed 'v. The driving ofthe overlap conveyor 9 is effected through a differential gear D thedrive of which is dependent on both speeds v and s. The driving membersof the differential gear are therefore connected with the driving meansMe, Go and Ms, Gs respectively. While the driven member of the geardrives the overlap band 9 at speed 11,. Preferably the ratios of thedifferential gear are made such that the speed but other ratios may bechosen where constructional features and conditions made that desirable.

The scheme of Figure 3 enables the attendant looking after the pile ofsheets to adjust the ejection speed s at all times, irrespective of thespeed of supply u, so that tidy piling is ensured. Also the sheetdelivery mechanism continues to run at the same speed when the rest ofthe machine is shut down until the sheets still on the conveyors havebeen stacked. At low working speeds the speed of the overlappingconveyor is mainly determined by the ejection speed; at high workingspeeds it will chiefly depend on the supply speed. So, as aboveexplained, the factor of risk (that is the length of free issue from thetake-01f conveyor) to which the machine is adjusted at low speedsdiminishes as the working speed increases, which is what is wanted forsatisfactory working, and necessitates exact adjustment of the overlapmechanism at low work-' ing speed.

The invention is not limited to the construction shown and described;modifications are possible which do not affect the fundamental notion.

7 V For example one member of the differential :gear may be driven notfrom parts moving at the supply speed .but from parts moving lat a speedderived zfrom the supply speed, for example trom parts moving (at the:take-ofi speed. Also one Ol'r'bOth of the driving members of thedifierential gear be driven through a variable :gear, so permittingalteration of the value T Instead-oi a differential Fgear other :knownmeans. may -be employed by which two speeds are comb'ine'd linearlyorotherwise to produce a third speed. 7

:1 claim:

-1. A machine for operating upon out sheets or paper fed thereinto froma previous operation at a predetermined linear speed, including :a firstconveyor andmeans for driving the conveyora't-a linear speed b, a secondconveyor receiving the sheets from said first conveyor and means v:Eordriving said second conveyorvat-a linear-speed m, a plurality of sheetdeliver-5 rolls andindependently controllable means for driving saidrolls at a peripheral speed s for stacking said sheets in a pile,whereby the first conveyor receives the cut sheets, the second -conveyorreceives the sheets irom the first conveyor in over-lapped condition,

and the delivery rolls receive sheets train the second (conveyor andoperate to stack them fin a pi1e,:said moli-drivingx-means beingindependent oii the means forrfeeding thesheets atsaid speed b,- andadditive transmission means coupling the s nond conveyor drivmg means ofspeed a -to both the first -convey0r driving means of speed h and to theroll-driving means of speed s, said transmission means being arranged sothat the;

various speeds are inter-related according to the equation wherein a, isa constant having a value between 2 and 10. r p

'2. A machine accordingfto claim 1,111 which Rlmasa value of B. I

GERAID STRECKER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 722293? B'egg r.. Mar. 1-7, 1903 1545315 Maxson July 14, 1 9251,638,38 Elilig Feb. 22, 182 2,291,261 Taylor .1. July 28, 19422,498,061 Apgar Feb. 21, 1950

